Phandroid notes that "with Verizon’s $15/month offer, if a user goes over their allotted bandwidth they will be charged an additional $15 to their monthly bill and given an extra 150 MB to work with as opposed to a flat data rate."

One of the commenters on Android Central expressed their belief that the pricing system for tablet data plans may be aimed at keeping users on Wi-Fi whenever possible when they are downloading a lot of data. That makes sense to me, especially if people will be using them to play movies, sucking up hundreds of megabytes at a time and slowing down other people's connection for two hours of use.